Surface-coated silicon-containing particulate material and rubbery composition and method of making same



SURFACE-COATED SILICON-CONTAINING PAR- TICULATE MATERIAL AND RUBBERYCOMPO- SITION AND lVIETHOD OF MAKING SAME Daniel S. Sears, HenricoCounty, Va., and Edwin B.

Newton, Akron, Ohio, assignors to The B. F. Goodrich Company, New York,N. Y., a corporation of New York No Drawing. Appiication June 12, 1951Serial No. 231,254

21 Claims. (Cl. 260-37) This invention relates to surface-coatedparticulate material and pertains more particularly to surface-coatedsilicon-containing particulate material and rubbery compositionsincluding same and method of making same.

It is an object of this invention to provide a finelydivided materialwhich is suitable as a rubber reinforcing pigment in reinforcinglight-colored and white rubbery compositions.

Another object of this invention is to provide a lightcolored orblue-white finely-divided surface-coated siliconcontaining reinforcingpigment for rubbery compositions which does not discolor light-coloredor white rubbery compositions to which it is added.

Still another object of this invention is to provide a finely-dividedsurface-coated silicon-containing reinforcing pigment for rubberycompositions which imparts to a rubbery composition to which it isaddedimproved abrasion resistance properties as compared'with conventional uncoated silicon-bearing rubber reinforcing pigmerits.

It is still another object of. this invention to provide a method ofmaking a light-colored or white rubbery composition having high abrasionresistance. f

Other objects of this invention will be apparent from the descriptionwhich follows.

Reinforcing. pigments have been added to rubbery compositions for manyyears to increase the hardness, stifiness, resistance to cutting,tearing and abrasion, and strength of the vulcanized compositions.Carbon blacks are generally employed as the reinforcing pigment in rub-'bery compositions mainly because the carbon black reinforcing pigmentshave been-the most satisfactory known reinforcing pigments readilyavailable. With an increasing demand for light-colored and white rubberyarticles, it has become apparent that carbon black reinforcing pigmentsare not completely satisfactory, since they are unable to satisfy thecolor requirement of reinforcing pigments for light-colored and whiterubbery compositions.

Finely-divided silicon-containing materials have been proposed assubstitutes for carbon black reinforcing pigments for rubberycompositions and the vulcanized rubbery compositions have beensatisfactory for many purposes; however the conventionalsilicon-containing reinforcing pigments do not impart to rubberycompositions a sufiiciently high resistance to abrasion to render themsatisfactory as reinforcing pigments for rubbery compositions which arerequired to exhibit high abrasion resistance properties. p

The present invention attains the aforementioned objectives providing afinely-divided or particulate material which imparts excellentproperties to rubbery compositions to which it is added. A reinforcingpigment made in accordance with this invention may be almost pure whitepermitting it to be incorporated into white or lightcolored rubberycompositions. Rubbery compositions within the purview of this inventioncomprise a finelydivided inorganic solid silicon-containing material,prefer ably a water-insoluble silicon-containing particulate material,having an organo-siloxane material coated over its outer face.

Among the solid inorganic silicon-containing particulate materials whichmay be coated with an organo-siloxane material in accordance with thisinvention are silica, silicon monoxide (or an intimate mixture ofsilicon and silica),-

polymeric silicon oxyimide (the preparation of which is y described inmy copencling application filed May 26, 1950,

Serial No. 164,619, now U. S. Patent 2,666,754), calcium silicate,magnesium silicate, leucite, analcite, nephelite, kaliophylite,hypersthene, diopside, acmite, jadeite, tremolite, melilite,sarc'olite,'garnet, pyrope, melonite, fayalite, muscovite, and the like.It is desirable that the silicon-containing particulate material berelatively stable in the presence of hydrogen chloride and consist of aparticulate material which has an average particle size of from 5 to 200millimicrons, preferably an average particle size of from 20 to 40millimicrons, Silica, silicon monoxide and polymeric silicon oxyimidehave proven particularly satisfactory as the finely-dividedsilicon-containing material for utilization in this invention.

Although any organo-siloxane material'may be used as the surface coatingfor the silicon-containing particulate material with an accompanyingimprovement inthe rubber reinforcing properties of the particulatematerial, it is desirable that the organo-siloxane material contain atleast one mono valent unit which has at least one olefinic' carbon tocarbon double bond C=C therein and preferably comprises a resilientorgano-siloxane resin.

A more preferred group of organo-siloxane materials for use in thisinvention is the group of polymeric organo-* siloxane condensationproducts obtained by the hydrolysis of organic halosilanes. Amongthe.organiczhalosilanes' which may be reacted with water to form polymericorgano-siloxanes are:

Methyl chlorosilane Dimethyl chlorosilane Trimethyl chlorosilane Methyldichlorosilane Methyl trichlorosilane Dimethyl dichlorosilane Ethylchlorosilane Ethyl dichlorosilane Ethyl trichlorosilane Diethylchlorosilane Diethyl dichlorosilane Triethyl chlorosilane Vinylchlorosilane Vinyl dichlorosilane Vinyl trichlorosilane Divinylchlorosilane Divinyl dichlorosilane Propyl chlorosilane Propyldichlorosilane Patented Nov. 4, 1958 Methyl dibromosilane Methyltribromosilane Dimethyl dibromosilane Ethyl dibromosilane Ethyltribromosilane Vinyl tribromosilane Propenyl bromosilane Phenylbromosilane Triphenyl. bromosilane Phenyl tribromosilane n-tetrahydrobenzyl tribromosilane A -tetrahydrobenzyl tribromosilane,

and the like.

Even more preferred foruse in this invention are polymeric.organosiloxane I condensation, ,productsobtained by the hydrolysis oforganic halosilanes containing at least one monovalent radical'having atleast one olefinic carbon to carbon. double bond. C=C therein, such as:

Vinyl chlorosilane Vinyl dichlorosilane.

Vinyl trichlorosilanc Vi'nyl' bromosilane Vinyl' dibromosilane Vinyltribromosilane Divinyl chl'orosilane Divinyl dichlorosilane Propenylehl'oros'il'ane' Propenylidichlorosilane' Propenyltrichlorosilane:Propenyllribromosilane 3-butenyl chlorosilane Z-butenyl. dichlorosilane3-buteny1 trichlorosilane Di-3i-butenyl'dichlorosilane 4-pentenyItrichloros'ilane' Z pentenyltrichlorosilane l butenyl tribro'rnosilane.3-pentenyl tribromosilane A -tetrahydrobenzyl trichlorosilane A-tetrahydrobenzyl tribromosilane A -tetrahydrobenzyl tribromosilane A-tetrahydrobenzyl trichlorosilane,

and the like.

The preparation of organo-siloxanes is well known in. the art, beingdescribed in various literature references including the GeneralElectric Company United States Patents No. 2,386,259, No. 2,390,378 andNo.,2,398,672.

The organo-siloxane material mayzbe applied to the surface of thesilicon-containing particulate material. in any manner conventionallyutilized incoating surfacesof finely divided or particulate materialshaving anaverage particle size of from 5 to 200 millimicrons;such.-as-by spraying the organo-siloxane onto the surfaces :of the particulate material,.the organo-siloxane material being dissolved in anappropriate volatile organic solvent if: necessary, or by introducing afinely divided vap'or'or mistof the organo-siloxane into anair-dispersion' of-the particulate material. The coated partic-ulatematerial is then dried, preferably by subjecting it to a' hot air streamhaving a temperature of from 75 to 150 C.',- although-the material maybe dried by merely exposing itto air at room temperature. In the case ofthe organo halosilanesg the hydrogen halide produced by hydrolysis isdriven offduring the drying step with the formation of a- 'silox'ane"resin;

It is desirable that the coating applied to the surface ofthesilicon-containing particulate material be of u nif'orm thickness andthat the weight offthe' coatingapplied to each particle of theparticulate material'be-frOm-DB to by weight of the uncoatedparticlerpreferablythe weight of the coating is from 5.to "13%" bywe'igliroftlie uncoated particle and preferably the coated sil Orr-comraining particulate materrahlias' average part cle 'sii'e'j.

'of' from 5 to 200'millimicrons, an average particle size material'scapable of reinforcement are natural rubber, such as caoutchouc and thelike which is essentially a conjugated polymer of isoprene, or syntheticrubber, such as therubbery polymers of open-chain conjugated dieneshaving from 4 to. 8 carbon atoms exemplified by butadiene- 1,3;2,3-dirnethyl butadiene'1,3; 1,4-dimethyl butadiene- 1,3 and thelike,-or' therubbery copolymers of these and similar conjugateddiolefins with each other or with copolyrnerizable monomeric materialscontaining a single ethylenic linkage, such as acrylonitrile, styrene,methyl acrylate,- methyl. rnethacrylate, ethyl acrylate, ethylmethacrylate, isobutyl'ene, or' similar materials or the rubberypolymersof. other conjugated dienes, such as chloroprene and the like.

To impart optimum reinforcement to the rubbery comp0sitions,'it ispreferable to incorporate from 30 to 89 parts by weight of oursurface-coated silicon-containingv reinforcing pigment-into the rubberycomposition based on 100 parts by Weight of rubbery material in thecomposition, although smaller-quantities of our pigment impart some.reinforcement to the rubbery composition, of

course. Appropriate compounding ingredients, such as fillers,accelerators, vulcanizing. agate-antioxidants, etc., may also be.employedinthe. rubbery compositions.

To clearly illustrate this'invention the following examplesare given,but it will be understood that the examples are intended merely asillustrations of the invention and arenot intended to limit the scope ofthe invention.

Example 1 was placed in an agitator and 5 percent by weight of.

propenyl trichlorosilane based on the weight, of'the.

silicon monoxide was introduced into the agitator in the form of a vaporor mist by passing a hot inert gas such as nitrogen through the liquidsilane maintained at a tem- V perature about 50 C. below the boilingpoint of the silane, the silicon monoxide being continuously agitatedduring; this operation. Water in an amount in excess of that requiredfor complete hydrolysis of the silane was likewise introduced into theagitator in the form of a vapor or mist suspended in air at the sametime and agitationof'the siliconmonoxide, silane and water wascontinned, the water. vapor reacting with the silane to formanorgano-siloxane condensation product over the surface of thesiliconmonoxide particles. The organo-siloxane coated siliconrnonoxidewas dried by passing air through theeoated particulate material whichalso removed any hydrogen chloride generated during the hydrolysis reaction. The water required for hydrolysis of the halosilane ispreferably introducedinto the reactor beforethe halosilane'or.simultaneously therewith. It may also be added subsequently to thehalosilane, or the particulate material, after being coated withhalo-silane, may simply be-allowed to standin'the. open at roomtemperature for about 24 hours, whereupon the moisture normally presentin theatmosphere will bring about hydrolysis; However,

- there'tends to be-some loss-of halosilane from the surface as there isat least enough to hydrolyze thehal'osilane employe'di I The followingrecip'e is a typical example-of arubbe'rry composition embodying thisinvention using naturalrubber: I

Material: Parts by weight Natural rubber 100.0 Organo-siloxane coatedsilicon monoxide described in Example 1 65.0 Zinc mzide 5,0 Pine tar 1.0Stearic acid 7 1.5 2-mercapto benzothiazole 1.0 Phenyl betanaphthylamine1.0 Sulfur 3.0 Didodecylamine 1.5

Total 179.0

The rubber and compounding ingredients were mixed in the usual manner ona roll mill and the resulting rubbery composition was vulcanized in amold at 280 F. for varying lengths of time. The tensile strength, at300% elongation and at rupture, of the test sample and the elongationvalue at the time of rupture of the vulcanized rubbery composition areindicated by the following data:

Tensile Percent 3 Strength at Elongation vulcanization Time at 280 F.Modulus, Breaking at the p. s. i. Point, Break p. s. i.

10 minutes 070 2, 970 680 20 minutes 1, 490 3, 400 550 40minutes 1, 6003. 530 540 60 minutes 1, 550 3, 630 550 90 minutes 1, 430 2, 950 520Example 2 Finely-divided silicon monoxide was coated as described inExample 1 except that 10% by weight of propenyl trichlorosilane based onthe weight of the silicon monoxide was introduced into the agitatorinstead of 5%.

The rubbery composition was compounded in the usual manner on a rollmill and the composition was vulcanized in a mold at 280 F. for varyinglengths of time, the

' following data being obtained upon testing the vulcanized samples:

Tensile Percent 300% Strength at Elongation vulcanization Time at 280 F.Modulus, Breaking at the p. s. i. Point, Break p. s. i.

minutes 1, 550 4, 200 000 minutes. 1, 960 4, 230 525 40 minutes" 2, 3204, 100 460 60 minutes- 2, 320 3, 600 415 90 minutes 2, 310 3, 840 480Example 3 i Finely-divided' silicon monoxide was coated as de- 6 scribedin Example 1 except that 10% by weight of diphenyl dichlorosilane basedon the weight of the silicon monoxide was introduced into the agitatorin place of the 5% by weight of propenyl trichlorosilane based on theweight of the silicon monoxide.

A typical recipe of a rubbery composition embodying. the organo-siloxanecoated silicon monoxide of this example is as follows:

Parts by weight Material:

Natural rubber 100.0 Organo-siloxane coated silicon monoxide describedin Example 3 65.0 Zinc oxide 5.0 Pine tar 1.0 Stearic acid 1.5Z-mercapto benzothiazole 1.0 Phenyl betanaphthylamine 1.0 Sulfur 3.0Didodecylamine 1.5

Total- 179.0

The: ingredients of this recipe were compounded on a roll mill in theusual manner and vulcanized in a mold at 280 F. for varying lengths oftime. The vulcanized composition exhibited the following properties:

- Tensile Percent. Y 300% Strength at Elongation vulcanization Time at280 F. Modulus, Breaking at the i p. s. i. Point, Break p. s. l.

1, 340 660 575 1, 190 3, 170 550 1, 2, 740 505 r 1, 3,170 550 I 90minutes 950 1; 910 460 Example 4- Finely-divided silicon monoxide wascoated as described in Example 1 except that 10% by weight of ethyltrichlorosilane basedon the weight of the silicon mon' oxide wasintroduced into the agitator in place of the 5% by weight of propenyltrichlorosilane based on the weight of the silicon monoxide.

A typical example of a rubbery composition incorporating thisorgano-siloxane coated silicon monoxide is as follows:

Material: Parts by weight Natural rubber 100.0 Organo-siloxanecoatedsilicon monoxide described in Example 4 65.0 Zinc oxide 5.0 Pinetar 1.0 Steari acid 1.5, Z-mercapto benzothiazole 1.0 Phenylbetanaphthylamine 1.0 Sulfur 3.0 Didodecylamine l 5 Total 179.0

The. ingredients ofthe recipe were compounded together ona roll mill inthe usual manner and the composition was vulcanized at 280 F. forvarying lengths of time. The following data -.were obtained whenvulcanized samples of the composition weretested:

Tensile Percent 300% Strengthat Elongation vulcanization Time at 280 F.Modulus, Breaking at the p. 5.1. Point, Break p. s. 1.

Finely-divided 'si'li'ca' having an average particle: diam eter from.to"200"milli'microns"wascoated as described in'Example 1 ex'cep'tth'at20% by weight'of prop'enyl 5 t'richlorosilane based on"th'e*w'eight ofsilica" was introdt'lced'. into the agitator instead 'of*5% by weight ofpro pehy l 'rrichlorosi'l'ane'; f

The following recipe is a typical example'of a rubberyeompositioni-incorporating this reinforcing pigment:

Materialz' Parts by weight Natural rubber 0' Organo-siloxane coated silca described in 5 Example 5 .22; L 60.0 Zinc oxide 5.0 Pine tar 1.0Stearicacid H I 1.5 Z-mercapto benzothiazole 1.0 Phenylbetanaphthylamine 1.0 Sulfur u 7 i 3.0 Didodecylamine 1.5

Total 174.0

The rubbery composition was prepared on a roll mill in the usual manner.and vulcanized at 280 F. for varyin'glengths of time- Vulcanized.samples of the rubbery composition exhibited the following properties:

Tensile" "Percent "Strengtlrat' Elongation Vulcanizaiidnflime M280? )3.Breakmgat the Point, Brea'k .p. s. l.

10 minutes 810 3, 510 700 20"r'ninutes 1:030 4;670 685 40minutes 1,070'4,680 "680 40 60.minutes 1,060 4, 160 .605 90minutes-.- 950 4;2i0' '625Finely-divided polymeric silicon oxyimide haying an average diameterfrom 5 to 200 millimicrons was coated as described in Example 1 exceptthat 10% by weight ofpropenyl trichlorosi'lane 'based' on the weightof'polymeric silicon oxyim'ide' was introduced 'into the agitator insteadof 5% byweight' of propenyltrihlorosilane.

.A typical example of'a rubberycomposition utilizing thisorgano-siloxane coated polymeric 'silicon'oxyirnide is asi follows?-Material: Parts-byweight Natural rubber 100.0 Organo-siloxane coatedpolymeric silicon oxyimide deseribed'in Example 6 65.0 Zinc oxide 5.0

Pine tar .1.0 Stearic acid "a-.. 1.5 2-mercapto benzothiazole: 1.0 Phenyl betanaphthylamine l'.0 Sulfur 3;0 Didodecylarnine 1.5

Total 179.0

The materials were mixed together on a roll mill in ;:the usual mannerand-vulcanized at 280 F. for varying lengths of time. T hefollowing-data .were obtained "when the composition at 285. F. for 30minutes. product having excellent physical properties, as indicated 8vulcanized samples of the" rubbery composition were tested:

Tensile Percent Strengthat Elongation Breaking at the Point, Break 10minutes:

40 minutes 60 minutes" minutes" 7 Example "7'Finely-divided..silica..having. an average. diameter from 5 to 200millimicrons. was coated-with an organo-siloxane by placingrelative'ly'pure silica in an. agitator and introducing 10% by. weightnflbutyldichlorosilane based. on. the. weight of silica ram-theagitatorfin the form. of 'a. finely-divided: vapor while, the silica wasbeing continuously .agi'tatedl Water in an amount in excess of thatrequiredfor the complete hydrolysis of the silane wassimultaneouslyintroduced'int o the agitator. in the .form. of a finely-divided vaporwhile continuously agitating the silane-coated silica. The hydrolizedparticulate product was then dried by exposing it to a hot air stream.

Atypical exampl'e ofa rubbery composition embodying this invention is.as follows:

Total 189K The ingredients were compounded together on aro'll millin-the usual 'manner andvulcanized at 275 F. for 40 minutes: A"vulcanized product exhibiting excellent physical properties wasobtained.

. Example..8.

-A typical example ofia rubber composition embodying this inventionusing synthetic rubber as the elastomeric material is as follows:

Material: Rubbery butadiene-styrene copolymer (75 :25)

(GR-S) 72% conversion 100.0 Organo-fsil'oxane. coated .silicon .monoxidedescribed. in Example 2 Zinc oxide.- Palm oil Stearic acid Tetramethylthiuram disulfide The composition was prepared by mixing theingredients. on a.roll.mill.in the usuallmannerandvulcanizing Avulcanized Total by tensile strength and elongation measurements,.wasobtained.

Example '9 A typical example of a rubbery composition embody- Parts byweight ing this invention using neoprene rubber as the elastomericmaterial is as follows:

Material: Parts by weight Rubbery chloroprene isoprene copolymer (GR-M)Organo-siloxane coated silica described in Example 30.0- Zinc oxide 15.0Magnesium oxide 4.5 Pine tar 2.0 Stearic acid 5.0

Total 156.5

The ingredients were compounded on a roll mill in the usual manner andvulcanized in a mold at 290 F. for 40 minutes. The vulcanized rubberycomposition exhibited excellent physical properties, as indicated bytensile strength and elongation measurements.

Vulcanized rubbery compositions within the purview of this inventionexhibit abrasion resistance properties equivalent to those exhibited byrubbery compositions reinforced with carbon black and much superior tothose exhibited by rubbery compositions reinforced with uncoatedsilicon-containing particulate reinforcing pigments as illustrated bythe following data:

1 Abrasion values were obtained by testing the vulcanized samples asdescribed in A. S. T. M. Standards on Rubber Products" underspecification D394-47, Method A.

Finely-divided coated silicon-containing pigments within the purview ofthis invention may be incorporated into light-colored to White rubberycompositions without irreparably discoloring the composition.

It is clear that obvious variations and modifications may be madewithout departing from the spirit and scope of this invention as definedin the appended claims.

We claim:

1. An elastomeric composition comprising a rubbery conjugated dienepolymer and a finely-divided inorganic solid silicon-containing materialcoated with an organosiloxane, the weight of the coating being from 0.3to 20% by weight of the uncoated material.

2. An elastomeric composition comprising a rubbery conjugated dienepolymer and a finely-divided waterinsoluble inorganic solidsilicon-containing material coated with an organo-siloxane, saidmaterial having an average particle diameter of 5 to 200 millimicronsand the weight of the coating being from 0.3 to 20% by weight of theuncoated material.

3. An elastomeric composition comprising a rubbery conjugated dienepolymer and a finely-divided inorganic solid silicon-containing materialcoated with a hydrolysis product of an organic halosilane containing atleast one monovalent radical having an ethylenic carbon to carbon doublebond, the weight of the coating being from 0.3 to 20% by weight of theuncoated material.

4. An elastomeric composition comprising 100 parts by weight of arubbery conjugated diene polymer and from.

30 to 80 parts by weight of a finely-divided inorganic solid assets-e a10 silicon-containing material ane, the weight of the coating being from5 to 13% by weight of the uncoated material.

5. An elastomeric composition comprising 100 parts by weight of arubbery conjugated diene polymer and from to 80 parts by weight of afinely-divided inorganic solid silicon-containing material coated withan organosiloxane, said material having an average particle diameter offrom 5 to 200 millimicrons and the weight of the coating being from 5 to13% by weight of the uncoated material.

6. An elastomeric composition comprising 100 parts by weight of arubbery conjugated diene polymer and from 30 to 80 parts by weight of afinely-divided inorganic solid silicon-containing material coated with acondensation product of water with an organic halosilane.

containing at least one monovalent radical having an ethylenic carbon tocarbon double bond, the weight of with an organo-siloxane, the weight ofthe coating being' from 5 to 13% by weight of the uncoated silica.

8. An elastomeric composition comprising 100 parts by weight of arubbery conjugated diene polymer and from 30 to parts by weight offinely-divided solid silicon monoxide coated with an organo-siloxane,the weight of the coating being from 5 to 13% by weight of the uncoatedsilicon monoxide.

9. An elastomeric composition comprising parts by weight of a rubberyconjugated diene polymer and from 30 to 80 parts by weight offinely-divided polymeric silicon oxyimide coated with anorgano-siloxane, the weight of the coating being from 5 to 13% by weightof the uncoated polymeric silicon oxyimide.

10. A composition of matter comprising finely-divided solid siliconmonoxide coated with an organo-siloxane, said composition of matterhaving an average particle diameter of from 5 to 200 millimicrons andthe weight of the coating being from 0.3 to 20% by weight of theuncoated silicon monoxide.

11. A composition of matter comprising finely-divided polymeric siliconoxyimide coated with an organo-siloxane, said composition of matterhaving an average particle diameter of from 5 to 200 millimicrons andthe weight of the coating being from 0.3 to 20% by weight of theuncoated polymeric silicon oxyimide.

12. The method of making a vulvanized rubbery composition comprisinguniformly dispersing a finely-divided inorganic solid silicon-containingmaterial coated with an organo-siloxane into a rubbery conjugated dienepolymer and vulcanizing the composition, the weight of the coating beingfrom 0.3 to 20% by weight of the uncoated material.

13. The method of making a vulcanized rubbery composition comprisinguniformly dispersing a finely-divided water-insoluble inorganic solidsilicon-containing material coated with a condensation product of waterwith an organic halosilane containing at least one monovalent radicalhaving an ethylenic carbon to carbon double bond into a rubberyconjugated diene polymer and vulcanizing the composition, the weight ofthe coating being from 0.3 to 20% by weight of the uncoated material.

14. An elastomeric composition comprising a rubbery conjugated dienepolymer and finely-divided solid silicon monoxide coated with anorgano-siloxane, the weight of the coating being from 0.3 to 20% byweight of the uncoated silicon monoxide.

15. An elastomeric composition comprising a rubbery conjugated dienepolymer and finely-divided solid silicon monoxide coated with anorgano-siloxane, said coated silicon monoxide having an average particlediameter of 5 to 200 millimicrons and the weight of the coating beingcoated with an organs-silos from 0.3 to 20% by weight of the uncoatedsilicon monoxide.

16. An elastomeric composition comprising a rubbery conjugated dienepolymer and finely-divided solid silicon monoxide coated with anorgano-siloxane containing at least one monovalent radical having anethylenic carbon-to-carbon double bond, the weight of the coating beingfrom 0.3 to 20% by' weight of the uncoated silicon monoxide.

17. An elastomeric composition comprising. 100 parts by weight of arubbery conjugated diene polymer and from 30 to 80 parts by weight offinely-divided solid silicon monoxide coated with an organo-siloxane,said coated'silicon monoxide having an average particle diameter of 5 to200. millimicrons and the weight of the coating being from 5 to 13% byweight of the uncoated silicon monoxide.

18. The method of making a vulcanized rubbery composition comprisinguniformly dispersing finely-divided inorganic solid silicon monoxidecoated with an organosiloxane into a rubbery conjugated diene polymerand vulcanizing the composition, the Weight of the coating being from0.3 to 20% by weight of the uncoated silicon monoxide.

19. A composition of matter comprising finely-divided silicon-containingmaterial selected from the group con- 12 sisting of silicon monoxide andpolymeric silicon oxy-- imide and coated with an organo-siloxane, saidcomposition of matter having an average particle diameter of from 5 to200 millimicrons and the weight of the coating being from 0.3 to 20% byweight of the uncoated material.

20. An. elastomericcomposition comprising a rubbery conjugated. dienepolymer and a finely-divided silica coated with. a saturated. aliphaticorgano-siloxane.

21. An elastomeric composition comprising a rubbery conjugated dienepolymer. and the reaction product of a finely-divided silica andanunsaturated acyclic halosilane in the presence of water.

References Cited in the file of this patent UNITED STATES PATENTS2,424,853 Safford July 29, 1947 2,439,689 Hyde Apr. 13, 1948 2,510,661Safiord June 6, 1950 2,528,606 Pedersen Nov. 7, 1950 2,563,555 SafiordAug. 7, 1951 2,578,605 Sears et al Dec. 11, 1951 2,610,167 Te GrotenhuisSept. 9, 1952 2,665,264 Brooks et. a1. Jan. 5, 1954

1. AN ELASTOMERIC COMPOSITION COMPRISING A RUBBERY CONJUGATED DIENEPOLYMER AND A FINELY-DIVIDED INORGANIC SOLID SILICON-CONTAINING MATERIALCOATED WITH AN ORGANOSILOXANE, THE WEIGHT OF THE COATING BEING FROM 0.3TO 20% BY WEIGHT OF THE UNCOATED MATERIAL.